I had a good friend who worked for UPS as a supervisor. He claimed it was the influence of the union that killed the company's good will. Between the strikers annoying commercial customers, and not boosting salaries for non-union temps and staff, bad attitude is the rule, and not the exception. UPS is swiftly becoming OOPS.
FedEx is still non-union.
Forget USPS - civil servants! Need I say more.